Nano News: 06/09/15

Closing in on the phenomenon of superconductivity with a two-dimensional atomic gas

Using an exotic quantum superfluid that originates in a two-dimensional atomic gas, researchers from Heidelberg University are closing in on the phenomenon of superconductivity. The team headed by Prof. Dr. Selim Jochim of the Institute for Physics is using this special gas as a model system to more easily study the largely unknown mechanism of the superfluid phase transition in 2D structures. The researchers hope to gain new insight into the so-called room-temperature superconductor, a hypothetical material that does not require cooling to achieve lossless conduction of electricity. The research results were published in the journal ("Observation of Pair Condensation in the Quasi-2D BEC-BCS Crossover").

Experimental setup to generate a two-dimensional ultracold quantum gas. (Photo: Martin Ries) (click on image to enlarge) Two of the most impressive phenomena that exhibit quantum mechanical behaviour in the “normal” world are superfluidity and its by-product, superconductivity. In physics, superfluidity is a state of matter in which a fluid loses all internal resistance. Superconductivity results when the electrons in a material behave like a superfluid liquid. They flow without encountering any friction, and the electrical resistance drops to zero. This state occurs only below a certain critical temperature, which is different for every superconductor. This behaviour is well understood in the conventional superconductor, in which the electrons move in three dimensions. But the problem is that the superconducting state can only be achieved at very cold temperatures well under negative 200 degrees Celsius. The necessary extensive cooling hampers a technological application, according to physicist Dr. Martin Ries. “For several years, it has been possible to produce high-temperature superconductors. Their critical temperature is significantly higher, but unfortunately still just under negative 130 degrees Celsius. Additionally, we only have a partial understanding of the way they work, making it difficult to develop better superconductors of this kind,” says the scientist, who is a member of Prof. Jochim’s research team.

Atomic gas in a magneto-optical trap. (Photo: Martin Ries) As Dr. Ries explains, science assumes that electrons can only move in two dimensions in high-temperature superconductors. So the Heidelberg physicists focused their research into superfluidity and superconductivity on two-dimensional structures. The superfluid transition is quite different between 2D and 3D structures, and the two-dimensional transition mechanism remains largely a mystery that is difficult to pin down theoretically. Although the so-called BKT theory did address it in the 1970s, it is only valid if the forces between the electrons are weak. “But what exactly happens with stronger forces is not known, and that is precisely the scenario of major significance,” says Dr. Ries. Jochim’s team of physicists has now succeeded in building a simple model system to perform a quantum simulation of the superfluid phase transition in 2D structures. They are using a two-dimensional ultracold gas captured in a laser trap. “We are able to create a ‘clean’ system that is easier to understand and in which the quantum mechanical behaviour of the particles resembles that of the electrons in two-dimensional structures,” reports Dr. Ries. It actually allowed the researchers to observe the transition into the superfluid phase at low temperatures and measure the critical temperature for any strength of interparticle forces. “This gives us the ability to more easily test the various theories for 2D superfluidity in the future,” explains Prof. Jochim, whose team is currently investigating the correlations in the superfluid phase. “Over the long term, we hope to gain a better understanding of high-temperature superconductivity that could lead to the development of a room-temperature superconductor at some point in the future.”

A step towards a Type 1 Diabetes vaccine by using nanotherapy

For the first time liposomes that imitate cells in the process of natural death have been used to treat Diabetes. Researchers at Germans Trias Research Institute (at UAB-Campus of International Excellence Sphere) generated liposomes in collaboration with professionals from the ICN2. Journal published the work ("Use of Autoantigen-Loaded Phosphatidylserine-Liposomes to Arrest Autoimmunity in Type 1 Diabetes"). The next steps are to confirm the efficacy in vivo with cells from patients and to carry out clinical trials to prevent the disease and to cure it. Two years ago, the Immunology of Diabetes Research Group at the Germans Trias Research Institute (at Universitat Autònoma de Barcelona - Campus of International Excellence Sphere) reported a new experimental immunotherapy that prevented the onset of Type 1 Diabetes in mice predisposed to the disease. This work led to more studies with the support of the Spanish Government, Catalan Government and private patrons with a keen interest in it. Thanks to this, the article published today in PLOS ONE describes a new step towards the creation of a vaccine, which in the medium-term could be capable of preventing and even curing the disease in humans. Initially the researchers avoided the destruction of the insulin-producing pancreatic cells (beta cells) in the body by modifying the individual’s immune cells, known as dendritic cells. This important step requires the extraction of the subjects' dendritic cells for their subsequent manipulation and re-injection. The process is complex and costly. In a new study with mice researchers have achieved the same effect with a much simpler process. Nanoparticles called liposomes are created in the laboratory; when they are introduced into the body they arrest the destruction of the beta cells and avoid Diabetes development. This technique could be a much better candidate for a human vaccine. The invention is commercially protected and an international patent has been applied for. Droplets of fat and water which can be produced on a large scale Liposomes have been used in several medical treatments. They are not cells, but droplets with an external fat membrane, similar to cell membranes. They can be made using a very specialized process, but one that is easy and safe and also easy to scale up. The key: beta cells in process of natural death To complete this study Germans Trias researchers have worked together with a ICREA group from the Catalan Institute for Nanoscience and Nanotechnology (ICN2). The ICN2 is a Severo Ochoa Center of Research Excellence located on Universitat Autònoma de Barcelona (UAB) Campus, and its mission is to seek nanotechnology solutions to challenges in the fields of biology, energy or technology. The diameter of the liposomes created for this collaborative work is from half to one micron. They were specifically generated to imitate beta cells of the pancreas that are in the process of programmed cell death (apoptosis). As the researchers showed during the previous studies, this is the way to prevent the body from destroying the beta cells and to allow it to recuperate immunological tolerance. The Catalan researchers are the first group in the world to use liposomes that imitate naturally dying cells to fight against Diabetes. The Universities of Barcelona and Lleida also contributed to this work. Next steps After showing that liposomes prevent the onset of Type 1 Diabetes in mice, the next steps are to test it in human cells in vitro, to start clinical trials on human candidates for preventive vaccination and to cure the disease by combining the vaccine with regenerative therapies. The Germans Trias Institute plans to carry out these steps with patients at the hospital and to optimize the product by dosage and guideline studies. It is also planned to optimize the product for personalization. To achieve these objectives more competitive funding will be necessary from public agencies. The group is also studying collaborations and investment opportunities from the pharmaceutical industry. Private funding continues to be important and the Germans Trias Institute is studying the possibility of organizing a local campaign. Growing incidence and complex consequences Type 1 Diabetes is an illness where the body does not recognize the beta cells of the pancreas as its own and destroys them. The organ produces less and less insulin, the hormone that allows us to process the sugar we eat. Patients must prick their fingers several times a day to check blood sugar levels and inject themselves with insulin in the stomach or other parts of the body. This constant control is not always easy and having too much or too little insulin can have severe consequences. The most serious is that in the long term hyperglycemia provokes retinal damage that can lead to blindness, renal insufficiency, destruction of nerve fibers or what is called "Diabetics Foot" where ulcers form, leading eventually to the need to amputate. The causes of the disease are unknown, although there are both genetic and environmental factors involved. About 0.3% of the population is affected and the incidence is increasing by 3-4% a year. It usually appears in children and young adults and it is incurable. This immunotherapy presents a possible solution for Type 1 Diabetes.

3D nano-images reveal 'bicycle spoke' structure of heart cells that may hold key heart attack clues

Newly released images revealing the ‘bicycle spoke’ structure of a heart cell may hold key clues to reducing damage from a heart attack. Research by Dr Ashraf Kitmitto and colleagues, from The University of Manchester’s Institute of Cardiovascular Sciences, provides new information as to why some cells don’t work properly following a heart attack.

Part of a healthy heart cell with a t-tubule ‘bicycle spoke’ structure. Using a novel type of electron microscopy, Dr Kitmitto and team produced 3D images of a healthy heart cell at nanoscopic scale which shows part of their structure is arranged like spokes on a wheel. These ‘spokes’, called T-tubules carry an electrical signal from the outside of the cell to the inside and are necessary for the coordinated transmission of the electrical impulse through the cell to enable the heart cells to contact and enable the heart to pump blood around the body. But following a heart attack, the T-tubules are lost in many areas and the electrical signal cannot be carried properly through the cells. The remaining T-tubules also appear to fuse and clump together forming very large, but distorted, ‘super-tubules’. This important research, funded by the British Heart Foundation, provides new insights into the structural changes that may contribute towards the development of heart failure and dangerous irregular heartbeats.

Part of a heart cell where t-tubules have been lost following a heart attack. The next step is to find out why this process happens following a heart attack and develop strategies to intervene to stop it from happening, for improved outcomes. There are an estimated 550,000 people across the UK living with heart failure, which is when the heart is permanently damaged following a heart attack. This research is being presented at the British Cardiovascular Society’s conference in Manchester on Tuesday. Dr Kitmitto, whose research was funded by the British Heart Foundation, said: “We’ve made major advances in treating people following a heart attack, so more people are surviving, but the treatments don’t address changes to the structure of the heart. “For the first time, we’ve been able to look, in 3D, at the nano-architecture of the cells around the damaged area of the heart and see the changes following a heart attack. “The regular pattern of T-tubules – like spokes on a wheel - is really important because it means the whole heart cell can receive the same information and it can contract together. “But following a heart attack that regular structure is lost, so some parts of the cell will get the signal and other parts won’t. “Now we can see what’s going on, the next step is to find out why and how we can intervene to prevent heart failure development.”

A ‘super-tubule’ (cyan) compared with a healthy t-tubule (pink). Dr Mike Knapton, associate medical director at the British Heart Foundation, said: “This interesting research and the beautiful images may hold key clues to reducing the permanent damage caused by a heart attack. “Because of the great strides our research has made in treating heart attacks, seven out of ten people now survive. “But this means there are an increasing number of people living with damaged heart muscle and heart failure. This research helps us to understand what happens following a heart attack and may lead to treatments to improve the quality of life for heart failure patients in the future.”